The field of the invention relates to glycerin by-products of biodiesel fuel production. In particular, the field of the invention related to the use of treated glycerin by-products of biodiesel fuel production as soil-amendments.
Biodiesel fuels (BDF) are important sustainable energy sources. They are available commercially for use as alternatives for replacement of fuels derived from coal, petroleum, and other fast dwindling and non-renewable fossil energy sources. BDF usually are esters of fatty acids with simple alcohols, principally methanol. The production of fatty acids for BDF manufacture may be based on a transesterification reaction of sodium methylate with animal or vegetable fats, which are esters of acids with glycerin (1,2,3-propanetriol). This is followed by separation of glycerin and other impurities from the methylated fatty acids, usually based on the fact that glycerin has a higher density than methylated fatty acids and sinks to the bottom of a batch reaction mixture. The BDF process thus results in accumulation of significant quantities of crude glycerin as by-product (i.e., “BDF glycerin”).
BDF glycerin commonly contains about 65-85% glycerin and other impurities that include acrolein, monoglycerides, and “high boiling compounds.” Production of commercial-grade glycerin, which is usually about 90-95% glycerin, requires removal of these impurities for potential markets. The increased cost of purification and the surfeit of glycerin in the world market today translate into a serious disposal problem for this by-product of BDF manufacture. Most crude glycerin today often is sold for burning as a source of energy. The oversupply of glycerin is considered one of the major problems in development of the biodiesel industry and new compositions and uses for BDF glycerin are desirable.